Circuit protective apparatus



April 24, 1962 G- RUDOLPH CIRCUIT PROTECTIVE APPARATUS Filed Sept. 27,1960 6 Easy? Inventor: e0 3e dq lp United States Patent ice 3,031,601CIRCUIT PROTECTIVE APPARATUS George Rudolph, Broornail, Pa., assignor toGeneral Electric Company, a corporation of New York Filed Sept. 27,1960, Ser. No. 53,813 Claims. Cl. 317-46) My invention relates tocircuit protective apparatus of the series-connected fuse and circuitbreaker type, and more particularly to fuse actuated tripping andlockout means for the circuit breaker in such a combination.

As indicated in Patent 2,358,215, Darling, it has been known for sometime that a fuse of the current-limiting type connected in seriescircuit relation with an overload responsive automatic circuit breakerand having its interrupting characteristics coordinated with theinterrupting characteristics of the circuit breaker will cooperatetherewith more effectively to protect an electric circuit againstoverload and short circuit currents than can be done with either of thedevices separately. It has also been recognized that for safetypurposes, and also to prevent single phasing in the event that only oneof the three fuses in a typical three-phase circuit is ruptured, meansshould be provided for tripping the circuit breaker and thusinterrupting all phases of the circuit in response to the rupturing ofany one or more of the series-connected fuses. In a typical arrangementof this character, however, such as shown in Patent 2,928,997, Edmunds,the circuit breaker tripping apparatus is automatically reset on openingof the circuit breaker, so that the circuit breaker may be manuallyreclosed immediately without replacement of the blown fuse. Thisarrangement also fails to give any indication of the location of theruptured fuse, or even of the fact that circuit breaker trippingoccurred as a result of fuse operation.

Accordingly it is a principal object of my invention to provide circuitbreaker tripping means responsive to interruption of a series-connectedfusible element to trip the circuit breaker and positively preclude itsreclosure in the absence of deliberate breaker resetting and fusereplacement.

It is a further object of my invention to provide tripping means for amultiphase circuit breaker which is responsive to rupture of aseries-connected fuse in any one phase of the circuit to trip thecircuit breaker and lock itself in tripping position.

It is still another object of my invention to provide, in a multi-phasecircuit breaker, lock-out type tripping means responsive to rupture of aseries-connected fuse in any phase to indicate the faulted phase and thenature of the interrupting action.

In carrying out my invention in one preferred embodiment for a typicalthree-phase circuit, I provide a threephase circuit breaker havingthermal or magnetic overload-responsive means, or both, in each phase ofthe circuit, all arranged to actuate a common movable trip shaft themovement of which for any reason is effective to release the circuitbreaker mechanism for automatic opening movement of the contacts. Inseries with the circuit breaker contacts there is provided in each phaseof the circuit a fusible element, preferably in the form of a fuse ofthe current-limiting type. For each phase of the circuit there isprovided an electromagnet having a movable armature responsive torupture of the fuse in that phase to actuate the trip shaft of thecircuit breaker. Positioned in mechanical interlocking relation witheach such tripping armature is provided a movable blocking lever whichis normally held by the electromagnet armature in a latched unblockingposition and is released by actuating movement of the armature to moveinto a position to block return movement of the armature. Connected toCTl Patented Apr. 24, 1952 the blocking lever is a manual reset shaftthe released movement of which indicates the fact and location of fuseoperation and the manual return movement of which serves to reset theblocking lever and electromagnet armature. Preferably thefuse-responsive electromagnet is connected to be energized by voltageappearing across the associated fuse when ruptured.

My invention will be more fully understood and its various objects andadvantages further appreciated by referring now to the followingdetailed specification taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a schematic electro-mechanical diagram of a three-phasecircuit breaker-fuse protective combination illustrating thefuse-responsive circuit breaker tripping mechanism in schematicperspective view;

FIG. 2 is a detailed side elevational view of the fuseresponsive lockouttripping mechanism, showing the mechanism in its normal latched oruntripped position; and

FIG. 3 is a partial side elevational view of the mechanism in a lockedout tripped condition.

Referring now to the drawing and particularly to FIG. 1, I have shown acircuit including line conductors 1, 2 and 3, each having connected inseries circuit relation therewith a fusible element 10 preferably of thecurrentlimiting type, and the separable contacts 11, 11a of athree-phase circuit breaker 12. The movable circuit breaker contacts 11are interconnected for simultaneous operation as indicated, and arebiased to open position by means of an actuating spring 13. A commonlatchtype operating mechanism 14 is provided for moving the circuitbreaker contacts to closed position (as shown) and holding them latchedin that position against their bias. The closing means is schematicallyindicated as an electromagnet 15, and the latching means is shown as amovable stop member 16 mounted upon a rotatable tripping shaft 17, andbiased to latching position by a spring 18.

The circuit breaker tripping shaft 17 is provided with three actuatingarms 19, 2t} and 21, each of which is associated through a similarelectromagnetic tripping mechanism with one phase of the three-phasecircuit. Each tripping mechanism comprises an electromagnet having anactuating winding 25 connected in parallel circuit relation with thefuse 10 in the associated phase of the circuit 1, 2, 3. These trippingmechanisms are identical in structure and are shown in greater detail atFIG. 2.

At FIG. 2 I have shown one of the fuse-responsive circuit breakertripping mechanisms arranged to engage the actuating arm 19 of thetripping shaft 17. The tripping mechanism comprises a supporting memberor frame 26 having mounted thereon an electromagnet comprising amagnetizable core member 27 carrying the actuating winding 25 and apivotally mounted movable armature member 23. The electromagneticarmature 28 is pivotally seated upon one leg of the core 27 at a point29 intermediate the ends of the armature, and is biased to unattractedposition by a spring 39. The armature 28 is shown in its unattractedposition and is pivotally movable to an attracted position in engagementwith a pole piece 27a of the core member 27. The armature is provided atone endwith a laterally projecting actuating arm 28a arranged to engageand move the trip lever 19 when the armature is moved to attractedposition. At its opposite end the armature 28 is provided with alatching shoulder 28b arranged for interlocking engagement with a movabe blocking member 31. The blocking member is shown as a pivotallymounted bar or lever pivoted intermediate its ends upon the frame 26 ata point 32. To the end of the blocking lever 31 remote from the armature28 is connected a reset and indicating rod 33, which passes through aportion 26a of the frame 26 and has at its end an indicating and resetbutton 34. The blocking member 31 is biased to move into a blockingposition beneath the latch shoulder 28b of the armature 28 by means of acompression spring 35 encircling the reset rod 33 and interposed betweenthe frame portion 26a and a seating washer 36 fixed to the rod 33.

At its end opposite the reset rod 33, the blocking member 31 is providedwith a projecting finger 31a arranged to be engaged by the latchingshoulder 28b when the armature 28 is in its unattracted position,thereby to hold the blocking lever 31 against its bias and in anunblocking position. It will be evident that when the armature 28 ismoved to its attracted position, the armature rotates in a clockwisedirection, as viewed in the drawing, raising the latching shoulder 28bout of the path of the finger 31a and permitting the finger 31a to movein a clockwise direction under the latching shoulder 28b. In thisposition, which has been illustrated in FIG. 3, the blocking member 31positively mechanically blocks return movement of the armature 28 to itsunattracted position until such time as the blocking member is returnedto its normal latched position by manual movement of the reset shaft 33.Upon such manual return of the blocking lever 31 to its latched positionshown, the finger 31a is removed from beneath the end of the armature23. The armature is then free to return to its unattracted positionunder the action of its biasing spring 30, and in this position itengages the finger 31a in the manner shown in FIG. 2, thereby to latchthe blocking member 31 in its unblocking position shown.

It will now be evident from the foregoing description that in operation,rupture of any one of the circuit fuses will cause the line voltageappearing across the open fuse to be applied to the actuating winding 25of the associated tripping magnet, thereby to attract the armature 28 ofthat magnet and to actuate the circuit breaker trip shaft 17. When thearmature 28, associated with the faulted phase, is actuated to engagethe trip shaft, it releases its interlocked blocking lever 31 formovement under its bias to blocking position beneath the latching end ofthe armature. Such movement of the blocking member 31 moves the resetrod 33 connected thereto to a position to indicate that the circuitbreaker tripping occurred as a result of fuse operation, and furtherindicates which phase of the circuit was responsible for the tripping.In this blocking position of the interlocked tripping armature andindicating linkage, as is clearly shown in FIG. 3, the armature 28 ispositively and mechanically blocked from return to its unattractedposition and thus held in tripping engagement with the associated arm19, or 21 of the trip shaft 17.. In a this manner the trip shaft 17 ispositively held in its tripping position and is thus disabled fromlatching closed the operating mechanism 14 of the circuit breaker 12.The circuit breaker operating mechanism is preferably of the trip-freetype such as shown for example in Patent 2,549,441, Favre, so that anyeffort to manually reclose the circuit breaker with the trip shaft 17held in its tripping position will be ineffective.

While I have illustrated only one preferred embodiment of my inventionby way of illustration, various modifications will occur to thoseskilled in the art. For example, it is evident that actuation of thetrip shaft 17 may be accomplished by engagement between the trip shaftand the blocking member 31, rather than between the trip shaft and thearmature 28. In like manner it will be evident that mechanical meanssuch as a switch responsive to rupturing of the circuit fuses may beutilized to energize the electromagnet in place of the shunt circuitconnection shown. It will be further apparent that the movable blockingmember may be provided with means for positively locking the circuitbreaker operating mechanism in open circuit position as Well as forblocking the circuit breaker trip mechanism in its tripped position.Accordingly, therefore, I wish to have it understood that I intend inthe appended claims to cover all such modifications as fall within thetrue spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric circuit protective apparatus comprising a circuit breakerhaving a pair of relatively movable cooperating switch contactsconnected in series circuit relation with a fusible element, operatingmechanism for opening and closing said switch contacts including meansbiasing said switch contacts to open circuit position and latching meansfor retaining said switch contacts in closed circuit position inopposition to said biasing means, tripping means for releasing saidlatching means including a movable trip member, an electromagnetincluding an actuating winding and having an armature movable toattracted position to actuate said trip member to a releasing position,a movable blocking member biased to a position to engage andmechanically hold said armature in said attracted position, a movablelatch member actuated by said armature upon movement to its unattractedposition to retain said blocking member against its bias in anunblocking position, manually operable resetting means for moving saidblocking member from said blocking position to said unblocking position,and means responsive to circuit interruption by said fusible element forenergizing said electromagnet.

2. An electric circuit protective apparatus comprising a circuit breakerhaving a pair of relatively movable cooperating switch contactsconnected in series circuit relation with a fusible element, operatingmeans for opening and closing said contacts including means biasing saidcontacts to open-circuit position and latching means for retaining saidswitch contacts in closed circuit position in opposition to said biasingmeans, tripping means for releasing said latching means including amovable trip member, an clectromagnet including an actuating winding andhaving an armature movable to attracted position to actuate said tripmember to a releasing position, a movable blocking member biased to aposition to engage and mechanically hold said armature in said attractedposition, said armature including a latching shoulder positioned whensaid armature is in its unattracted position to engage said blockingmember and retain it against its bias in an unblocking position,manually operable resetting and indicating means connected to saidblocking member for returning said blocking member to said unblockingposition, and means responsive to circuit interruption by said fusibleelement for energizing said electromagnet.

3. An electric circuit protective apparatus comprising a circuit breakerhaving a pair of relatively movable cooperating switch contactsconnected in series circuit relation with a fusible element in eachphase of a multiphase circuit, operating mechanism for simultaneouslyopening and closing said switch contacts including means biasing saidswitch contacts to open-circuit position and latching means forretaining said contacts in closed-circuit position in opposition to saidbiasing means, tripping means for releasing said latching meansincluding a movable trip member, and a tripping mechanism associatedwith each phase of said circuit, each said tripping mechanism comprisingan electromagnet including an actuating winding and having an armaturemovable to an attracted position to actuate said trip member to areleasing position, a

movable blocking member associated with each said armature, each saidblocking member being biased to a position to engage and mechanicallyhold its associated armature in attracted position, each said armatureincluding a latching shoulder positioned when said armature is in itsunattracted position to engage the associated blocking member and retainsaid blocking member against its bias in an unblocking position,separate manually operable resetting and indicating means connected toeach said blocking member for individually returning said blockingmembers to their unblocliing positions, and means responsive to circuitinterruption by the fusible element in each said circuit phase toenergize a respective one of said electromagnets.

4. An electric circuit protective apparatus as claimed in claim 3 inwhich the electromagnets are connected for energization across theterminals of the fusible elements respectively.

5. An electric circuit protective apparatus comprising a circuit breakerhaving a pair of relatively movable cooperating switch contactsconnected in series circuit relation with a fusible element, operatingmechanism for opening and closing said switch contacts including meansbiasing said switch contacts to open circuit position and latching meansfor retaining said contacts in closed circuit position in opposition tosaid biasing means, tripping means for releasing said latching meansincluding a movable trip member, an electromagnet including an actuatingwinding and having an armature biased to an unattracted position, amovable blocking member biased into latching engagement with saidarmature in said unattracted position and releasable by movement of saidarmature to said attracted position to move into blocking engagementwith said armature and prevent return movement of said armature, meansoperable in response to movement of said armature to said attractedposition to actuate said trip member to a releasing position, and meansresponsive to circuit interruption by said fusible element to energizesaid electromagnet to attract said armature.

References Cited in the file of this patent UNITED STATES PATENTS1,288,820 Braunworth Dec. 24, 1918 1,934,264 Hefner Nov. 7, 19332,559,913 Forshee July 10, 1951 2,928,997 Edmunds Mar. 15, 1960

